The invention described in this application pertains mainly to the field of preserving agricultural products by drying. The principal means used to prevent spoilage of harvested grains, beans and legumes is removal of moisture as soon as practicable after harvest (or even on the stalk before harvest, as with corn). In locations and seasons where the ambient air humidity is low, the drying is often done simply by exposure to air. Thus, this invention also pertains to the field of air drying. It pertains more specifically to the field of forced warm air drying, because air drying may be augmented by preheating of the air, and by forcing the air through the material to be dried.
The invention pertains as well to transportation of agricultural products. Grains, beans, legumes, and tree nuts are typically transported after harvest in open-topped rectangular conveyances such as dump cars and box trailers. Box trailers are most commonly used for legumes such as peanuts. These trailers may be emptied by tilting or by positioning on a rollover dump apparatus. Hopper trailers may also be used, which, while being more expensive than box trailers, may be unloaded in a level position and therefore do not require expensive tilt or roll dump equipment.
Hopper cars and trailers may be modified as described below to dry, as well as transport, agricultural products. Additional modifications, also described further below, may also be made to improve the ease of unloading such containers in a level position by a redesign of the prior art slide or drop gates at the bottom of the hopper(s).
The drying and transporting functions have been combined in the prior art in peanut production by application of warm air through the sides or bottoms of trailers. This reduces handling, because the drying is attempted in the same container that is being used for transportation. The chief drawback, however, is that drying is not uniform. When air is applied to one or two openings in the side or bottom of a trailer to dry peanuts, for example, the path of the air through the peanuts is uneven. As a result, some zones within the trailer dry faster than others. The result is that some of the nuts are over-dried and some are under-dried with attendant quality variation and potential for spoilage.